1. Field of the Invention
The present invention is directed to an improvement in the fabrication of metallic honeycomb core and more particularly, but not by way of limitation, to an automatic machine for rapidly manufacturing metallic honeycomb core material having a finite width and precise height from a continuous metal foil strip material, which honeycomb core is suitable for ultimate use substantially as it is fabricated.
2. Description of the Related Art
Many manufacturing processes, such as welding, require that several parts be brought together and assembled precisely at a work station, held there in such assembled relation for the duration of the welding period and then moved from the work area to make way for successive parts to be introduced, assembled, and acted upon therein. An example of this type arises in the manufacture of metallic honeycomb. In fabricating this honeycomb core, strip feed and positioning means comprising inter-nesting electrode and indexing pins juxtaposed sections of corrugated metal ribbon or strips so that troughs of one strip rest on the crests of an adjacent strip. The strips are then held in this position while contacting electrode pins on the upper and lower welding assemblies and welding wheels on the weld wheel assemblies pass welding current through the abutting nodes of the adjacent crests and troughs to weld the same together and form adjacent cells of the honeycomb core. When selected crests and troughs have been welded together, the electrode pins and welding members are withdrawn from the formed cell and, following the shuttling of the core by the indexing pins, the indexing pins are re-inserted and re-applied as the process is repeated, as necessary, to complete the desired core.
For a completely satisfactory result in providing high quality honeycomb core, the juxtapositioning of the strip sections must be very precise; the pressure, movement and electrical contacting of the welding members must be critically controlled and precision positioning, alignment, and movement of the parts must prevail repetitively in the cell-to-cell formation though the length and width of the honeycomb core.
Various honeycomb core machines have heretofore been proposed and used with varying degrees of success. Examples of prior art machines for producing honeycomb core are found in U.S. Pat. Nos. 2,927,991 by W. A. Schoelz; 3,070,686 by P. Vinson et al.; 3,077,533 by F. H. Rohr et al.; 3,092,711 by H. B. Bennett et al. and 3,108,368 by C. W. Christinan.
In general, these prior art machines require that the maximum width of the honeycomb core material is either dictated by the number of weld electrode positions or that the honeycomb core, or such portion produced of it, be horizontally translated back and forth by the operator or other means so that a width greater than the number of weld electrode positions can be accomplished. The prior art machines also produced wavy or uneven surface core which had to be later trued due to the use of a single set of wheel weld electrodes. Also, in order to get a precise dimensional honeycomb core material, a thick blanket was produced initially, then this blanket was sliced or machined to obtain the desired width, length and thickness. This operation is very labor intensive and produces a considerable amount of waste.
Another prior art machine of interest is seen in U.S. Pat. No. 4,642,436 by W. F. Rethwish et al, which patent is assigned to the present assignee. This patent discloses an automatic machine for producing a continuous length of honeycomb core material of finite width and height from a continuous strip of corrugated ribbon material. This machine includes a main frame and transport assemblies. The transport assembly carries a corrugated ribbon laying means which positions a layer of corrugated ribbon strip between horizontally displaced upper and lower weld electrode assemblies as the transport assembly shuttles back and forth across the main frame assembly. The transport assembly also carries a welding means which is vertically translatable to a welding position in contact with the layer of corrugated ribbon strip.
The operation of this machine provides for the transport assembly to lay a predetermined portion of the corrugated ribbon between the upper and lower weld electrode assemblies commensurate with the width of the welding means. The welding means is then actuated to weld such portion of the corrugated ribbon strip to a previously positioned portion of such ribbon strip. The transport assembly is then moved along the main frame a predetermined distance to lay an additional portion of corrugated ribbon and then stopped where the welding process is repeated. This transport, dwell for welding, and continued transport of the transport assemblies along a track on the main frame is repeated until the desired width of honeycomb core has been fabricated. While honeycomb core fabricated by this machine has a finite width and height it is desired to fabricate such honeycomb core of equal or enhanced quality on a more rapid basis.
A need therefore exists for an improved machine that can rapidly fabricate metallic honeycomb core having a predetermined width and a precise height and which is suitable for ultimate use substantially as fabricated without having to be subjected to further processing in order to prepare such core for ultimate use. The fabrication of honeycomb core having a precise net height without having to be subjected to further processing is very desirable since a need for net metallic core has substantially increased. Net metallic core is advantageously used in the manufacture of metallic honeycomb core panels wherein the metal honeycomb core is bonded to metal face skins by a suitable metal joining process which requires all facing surfaces of such core to precisely meet the planar surfaces of the metal faces. Net metal core is also desirable in the manufacture of honeycomb core panels that are adhesively bonded together.
Yet another prior art metal honeycomb welding apparatus of interest is U.S. Pat. No. 4,013,865 issued to E. E. Jones which is directed to a metal honeycomb welding apparatus having a number of finger electrodes that are insertable into a honeycomb core panel. A welding means provides for carrying a corrugated metal strip to a welding station by means of weld heads which position such strip for welding. The weld heads include welding elongated members which advance into a welding position where a number of "tit-like" projections on an edge face of a corrugated metal strip are to be welded. After welding of one weld face of the strip, the welding elongated members are withdrawn, indexed and again translated forwardly to another welding position. Such cycle is repeated until the number of desired welds is accomplished. This apparatus does not appear to fabricate metallic honeycomb core having a precise net vertical height and it is obviously limited in the speed with which it can fabricate metal core.
It is a principal objective of the present invention to provide an improved machine to fabricate at high production rates a continuous length of metallic honeycomb core of finite width and precise height that is substantially suitable for ultimate use as it exits the machine.
It is a second principal objective of the present invention to provide an improved machine for rapidly fabricating honeycomb core that is substantially net in height and of great uniformity and high quality.
It is another objective of the present invention to provide a machine that produces net metallic honeycomb core at relatively high production rates.
It is another objective of the present invention to provide a machine for rapidly fabricating metallic honeycomb core which has uniform high quality welds at abutting nodes of the continuous metal foil strip comprising the core.
It is yet another objective of the present invention to provide a machine for fabricating metallic net honeycomb core by reversibly feeding a continuous strip of metal foil successively through a plurality of sequential weld stations positioned along a main frame to fabricate the net honeycomb core in one relatively continuous movement.
It is another objective of the present invention to provide a machine for fabrication of metallic net honeycomb core by sequentially welding a set of nodes of a continuous deformed metal strip, as it is positioned in place with a series of non-translating weld head assemblies which span the entire width of the honeycomb core.
It is still another objective of the present invention to provide a machine for fabricating net metallic honeycomb core from a continuous metal foil strip which provides for upward rotation of the foil positioning mechanism and welding mechanism from their operative positions to expedite maintenance of the machine and to reduce the time required to reconfigure the machine to make honeycomb core of another size.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and application of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.